Attachment device

ABSTRACT

A thermoelectric magnet for interconnecting metallic elements utilizing a thermocouple having an insulated heat-producing chemical charge at the &#39;&#39;&#39;&#39;hot&#39;&#39;&#39;&#39; junction thereof which is activated on command and permanently magnetizes the core material.

United States Patent 1 Erickson et a1.

ATTACHMENT DEVICE inventors: Porter W. Erickson; Alvin G.

l'lellfritmch, both of Silver Spring, Md.

The United States of America as represented by the Secretary of theNavy, Washington, DC.

Filed: July 2, 1968 Appl. No.: 742,975

Assignee:

US. Cl. 136/200; 136/205; 317/133.5 Int. Cl. H0lh 47/26 Field of Search136/200, 205; 317/123,

References Cited UNITED STATES PATENTS 9/1945 Paille 317/123 1 June 24,1975 2,400,384 5/1946 Betz 317/[23 2,720,614 10/1955 Cairns, Jr 317/1232,767,355 10/1956 Wolff 317/123 Primary Examiner--Ver1in R. PendegrassAttorney, Agent, or FirmR. S. Sciascia; .1. A. Cooke ABSTRACT Athermoelectric magnet for interconnecting metallic elements utilizing athermocoup1e having an insulated heat-producing chemical charge at thehot" junction thereof which is activated on command and permanentlymagnetizes the core material.

10 Claims, 4 Drawing Figures ATTACHMENT DEVICE BACKGROUND OF THEINVENTION The invention generally relates to attaching devices and moreparticularly to a magnetic type attaching device for interconnectingmetallic elements.

The present methods and apparatus used to clandestinely attach anordnance device such as a mine or the like to the bottom area of a shipinvolves the use of permanent magnets which are formed as part of themine. This apparatus which is termed a Limpet-type mine has beendiscovered to have severe limitations in the use thereof because theswimmer, whose function is to attach the device to the bottom area ofthe ship is required to navigate underwater by compass in view of thedepth and darkness at which he is operating. Since the magnetic fieldsurrounding the Limpet mine causes the compass needle to acterratically, the swimmer is unable rely on his compass to aid him insearching out his target. Therefore, the swimmer cannot hold the mine inhis hand. Dragging the mine behind by a rope or the like would subjectthe mine to shock if it comes into contact with a solid surface andwould increase the liklehood of snagging the mine on various impedimentspresent under the water.

A further problem arises upon the application of the metallic magnetmine to the metallic surface of the ships hull. It was discovered thatsince the Limpet mine incorporated a strong permanent magnet, it wasalmost impossible to bring the mine in contact with the steel plate of ahull without creating a loud noise upon magnetic siezure. Such noise issubject to detection by acoustic sensors and indicates the presence ofactivity adjacent to the ship. This, in turn, may result in the swimmersbeing captured and the mine located.

SUMMARY OF THE INVENTION Accordingly, it is an object of the presentinvention to provide an improved device for magnetically attachingferromagnetic elements together.

Another object of this invention is the provision of a magneticattaching device which is capable of activation immediately prior to usethereof.

Still another object of this invention is to provide a magneticattaching device having high magnetic attraction characteristics andcapable of interconnecting ferromagnetic elements without creating anynoise upon the application of the attaching device to the elements.

A still further object of the present invention is to provide a magneticattaching device which is normally in an inoperative mode and thereforemay be carried with magnetically sensitive devices without affecting theoperation of the same.

An additional object of the present invention is the provision of amagnetic attaching device which can be carried together with a magneticcompass used for guidance without affecting the operation of saidcompass.

According to the present invention, the foregoing and other objects areattained by a magnetic attaching device having an electromagnetactivated by a thermocouple, the thermocouple being activated, in turn,by an insulated heat producing chemical charge adjacent to the hotjunction of the thermocouple and activated on command. Upon activationof the thermocouple, the core material of the electromagnet becomes apermanent magnet.

DESCRIPTION OF THE DRAWING A more complete appreciation of the inventionand many of the attendant advantages thereof will be readily appreciatedas the same becomes better understood by reference to the followingdetailed description when considered in connection with the accompanyingdrawings wherein:

FIG. 1 is an elevation view of a preferred embodiment of the invention;

FIG. 2 is a section of the device taken along the lines 22 of FIG. 1;

FIG. 3 is a sectional view taken along lines 3-3 of FIG. 1', and

FIG. 4 is a cross-sectional view taken along the lines 44 of FIG. 2.

BRIEF DESCRIPTION OF PREFERRED EMBODIMENT Referring now to the drawingswherein like reference characters designate identical or correspondingparts throughout the several views, and more particularly to FIGS. 1 and2 thereof, a magnetic attaching device generally indicated at 10 isillustrated as interconnecting an explosive mine shown generally at 12to the hull of a ship generally indicated at 14 and floating in a watermedium 15. The device 10 includes basically a thermoelectric magnet 16actuated by a heat producing chemical charge assembly 18. Againreferring to FIGS. 1 and 2 the thermoelectric magnet 16 is of thegeneral type manufactured by the Central Scientific Company andgenerally shown by U.S. Pat. No. 1,893,748. This apparatus 16 comprisesa pair of bars 20, only one of which will be described, constructed ofheavy conductive material, such as copper or the like, of squarecrosssectional configuration bent into the form of a coil 22 andterminating in a thermocouple generally indicated at 23. Thermocouple23, in turn, comprises a pair of arms 24 and 25 extending from the coil22 and across which is connected, as by brazing, welding, or the like, arod 26 of a metallic material dissimilar to the material of the arms 24and 2S, and may be a material such as constantan or the like. Theconnection of rod 26 at arm 24 forms the hot junction 27 of thethermocouple 23 while the connection of rod 26 at arm 25 forms the cold"junction 28 of the thermocouple 23.

The bars 20 are partially housed within a cylindrical block 30constructed of any ferrous material capable of being permanentlymagnetized such as Cunico, 34% cobalt steel or the like. The block 30has each end 32 thereof ground flat and polished, in which has beenmilled or otherwise formed a circular groove 34 for positioning the coil22 of the bar 20.

As shown more clearly in FIG. 2, the arms 24 and 25 are offset inwardlyas at 36 in order to provide the device 10 with a pair of completelyclear vertical surfaces for permitting the mine 12 and hull 14 to becoupled to the device and as shown in FIG. 4, to form a supportingsurface 42 at the junction of arms 24 to which the assembly 18 isthermally connected.

Turning now to FIGS. 3 and 4, the heat-producing chemical chargeassembly 18 is constructed of a barrel 40 flattened along a portion ofthe surface thereof at 42 and connected by a thermal connection as bybrazing, welding or the like to the arms 24 adjacent the hot junction27. The barrel 40 is externally threaded at 43 and has an internal boreat 44 and counterbore at 46 to receive a heat generating cartridge 50 ofa thermitetype pyrotechnic mixture 52 which is explosively actuated by apercussion type primer charge 54. Such cartridges 50 are of the typeknown and used in the soldering iron art and is of the type manufacturedby the Kemode Manufacturing Company under the tradename of Quilt-Shot.This cartridge contains ten thousand calories of heat energy supplied bythe thermite mixture which is sealed in the steel shell. The temperaturegenerated by the cartridge is in the order of magnitude of 800 to 900Fand such temperature may be maintained for a period of 6 to 8 minutes.The generation of such high degree of heat over such long periods oftime enables the hot" junction 27 to be heated to a sufficiently hightemperature differential with respect to the cold junction 28 the latterof which is exposed to the surrounding water medium 15. Thisdifferential in temperature between the two junctions causes a currentto flow through the bar and permanently magnetize the cylindrical block30. It should be understood that although not shown, the arm 24 andbarrel 40 can be further coated or surrounded with an insulating mediumto minimize the dissipation of heat energy from the cartridge 50 to thesurrounding water medium 15. It should further be understood that inorder to insulate the heat producing cartridge 50 from the surroundingwater medium 15, it is within the scope of the present invention toprovide a ceramic or other lining between the cartridge 50 and the sideof the barrel 40 which is remote from the hotjunction 27 of bar 20 tothereby insure that more of the heat produced by the actuation ofcartridge 50 passes to the arm 24 to thereby attain a greatertemperature differential between the arms 24 and and create a greatercurrent through the coil 22 and provide a higher degree of efficiency inmagnetizing the cylindrical block 30.

The primer charge 54 of the cartridge 50 is fired by a firing mechanism60 now to be described. The barrel 40 at its externally threadedcylindrical portion 43 threadably receives a firing chamber 62 which isinternally threaded at 64. Chamber 62 includes an annular O-ring seal 66to maintain the assembly 18 in a water tight condition. A firing pin 68is slideably retained in the chamber 62 and is moveably disposed betweena safe and firing position. A compression spring 74 urges the firing pin68 to the firing position. The pin 68 is withdrawable by knob 78 to thesafe position and is held in such position by a safety pin 80 which isslideably and removably positioned within the chamber 62 and passesthrough the firing pin 68 to retain the same in the safe position.

It should be understood that firing mechanisms other than that shownherein may be utilized to actuate the cartridge 50 and that otherthermite-type pyrotechnic devices may be used other than the cartridge50 to generate the heat required to magnetize the cylindrical block 30.

In operation, the swimmer carries the magnetic attaching device 10 inthe inoperative mode and the mine 12 to the hull of a ship 14. Theswimmer locates a smooth and flattened surface of the hull l4 andpositions one end 32 of the block against the metallic hull 14. At thistime the pin 80 is removed from the chamber 62. The firing pin 68 isurged by spring 74 into engagement with the primer charge 54 whichdeflagrates the mixture 52 of cartridge 50. The heat produced bycartridge 50 is transferred to the copper bars 20 which in turn, due tothe temperature differential between the hot" and cold" junctions 27 and28, respectively, causes a current to flow through the coil 22 andpermanently magnetize the block 30. A magnetic coupling is then attainedbetween the device 10 and the hull of the ship 14. Similarly, the otherend 32 of block 30 has been transformed into a permanent magnet and theferromagnetic mine 12 be brought into contact therewith to be coupledthereby to the hull 14 of the ship.

By reason of this mechanism and the actuation thereof the swimmer is notinhibited in his use of a magnetic compass to locate the hull of theship since the magnetic attaching device is in an inoperative modeduring the time the swimmer is using the magnetic compass and thereforethe compass will be unaffected thereby. Additionally, the noise whichwould be created by applying a strong permanent magnet to the hull ofthe ship is avoided since the magnetic forces of attraction are not setup until the magnetic attaching device 10 is in contact and abutmentwith the hull 14.

it is to be further understood that although two magnetized surfaces areillustrated and disclosed above, only one such surface may be utilizedwithout departing from the scope of the present invention. In lieu ofthe other magnetized surface to which the mine 12 is applied there maybe placed a mechanical connection such as a hook or the like to whichthe mine may be suspended. This deviation may be required in theinstance where the mine to be attached is not ferromagnetic.

Obviously, numerous other modifications and variations of the presentinvention are possible in the light of the above teachings. It istherefore to be understood that within the scope of the appended claimsthe invention may be practiced otherwise than as specifically describedherein.

What is claimed as new and desired to be secured by Letters Patent ofthe United States is:

l. A magnetic device attachable to a ferromagnetic surface comprising:

a core;

coil means for said core;

thermocouple means energizing said core said thermocouple means having ahot" junction and a cold junction;

chemical charge means for producing heat energy and coupled to said hotjunction;

said chemical charge means being selectively activated to producesufficient heat at said hot junction to cause current to flow throughsaid coil means and magnetize said core.

2. The device as defined in claim 1 wherein said core is constructed ofmaterial capable of being permanently magnetized and said charge meansis capable of providing sufficient heat to permanently magnetize saidcore.

3. The device as defined in claim 2 wherein said thermocouple meansincludes:

a pair of arms extending from said coil means, said arms beingconstructed of similar conductive material;

a bar member formed of a material dissimilar to said arms and connectedto one of said arms to form said *hot" junction and to the other of saidarms to form said cold" junction.

4. The device as defined in claim 3 wherein said chemical charge meansincludes:

a cartridge;

said cartridge containing a high caloric, thermitetype mixture forproducing sufficient heat energy to magnetize said core;

primer charge means adjacent said mixture for igniting said mixture uponreceipt of an impacting force.

5. The device as defined in claim 4 further including:

a barrel member for receiving at least one of said cartridgcs;

said barrel member being in thermal communication with said hotjunction;

firing means associated with said barrel member for selective impactingengagement with said primer charge means.

6. The device as defined in claim 5 wherein said firing means includes:

firing pin means for engaging said primer charge means and movablebetween an impacting position and a withdrawn position;

spring means urging said pin means to said impacting position;

trigger means releasably retaining said pin means in said withdrawnposition against the urging of said spring means.

7. The device as defined in claim 6 wherein said coil means and saiddepending arms are constructed of copper and said bar member is formedof constantan.

8. The device as defined in claim 1 wherein said chemical charge meansincludes:

a cartridge;

said cartridge containing a high caloric, thermitetype mixture forproducing sufficient heat energy to magnetize said core;

primer charge means adjacent said mixture for igniting said mixture uponreceipt of an impacting force.

9. The device as defined in claim 8 further including:

a barrel member for receiving at least one of said cartridges;

said barrel member being in thermal communication with said hot"junction;

firing means associated with said barrel member for selective impactingengagement with said primer charge means.

10. The device as defined in claim 1 wherein a pair of coils surroundsaid core and thermocouple means is connected to each of said coils.

1. A magnetic device attachable to a ferromagnetic surface comprising: acore; coil means for said core; thermocouple means energizing said coresaid thermocouple means having a ''''hot'''' junction and a ''''cold''''junction; chemical charge means for producing heat energy and coupled tosaid ''''hot'''' junction; said chemical charge means being selectivelyactivated to produce sufficient heat at said ''''hot'''' junction tocause current to flow through said coil means and magnetize said core.2. The device as defined in claim 1 wherein said core is constructed ofmaterial capable of being permanently magnetized and said charge meansis capable of providing sufficient heat to permanently magnetize saidcore.
 3. The device as defined in claim 2 wherein said thermocouplemeans includes: a pair of arms extending from said coil means, said armsbeing constructed of similar conductive material; a bar member formed ofa material dissimilar to said arms and connected to one of said arms toform said ''''hot'''' junction and to the other of said arms to formsaid ''''cold'''' junction.
 4. The device as defined in claim 3 whereinsaid chemical charge means includes: a cartridge; said cartridgecontaining a high caloric, thermite-type mixture for producingsufficient heat energy to magnetize said core; primer charge meansadjacent said mixture for igniting said mixture upon receipt of animpacting force.
 5. The device as defined in claim 4 further including:a barrel member for receiving at least one of said cartridges; saidbarrel member being in thermal communication with said ''''hot''''junction; firing means associated with said barrel member for selectiveimpacting engagement with said primer charge means.
 6. The device asdefined in claim 5 wherein said firing means includes: firing pin meansfor engaging said primer charge means and movable between an impactingposition and a withdrawn position; spring means urging said pin means tosaid impacting position; trigger means releasably retaining said pinmeans in said withdrawn position against the urging of said springmeans.
 7. The device as defined in claim 6 wherein said coil means andsaid depending arms are constructed of copper and said bar member isformed of constantan.
 8. The device as defined in claim 1 wherein saidchemical charge means includes: a cartridge; said cartridge containing ahigh caloric, thermite-type mixture for producing sufficient heat energyto magnetize said core; primer charge means adjacent said mixture forigniting said mixture upon receipt of an impacting force.
 9. The deviceas defined in claim 8 further including: a barrel member for receivingat least one of said cartridges; said barrel member being in thermalcommunication with said ''''hot'''' junction; firing means associatedwith said barrel member for selective impacting engagement with saidprimer charge means.
 10. The device as defined in claim 1 wHerein a pairof coils surround said core and thermocouple means is connected to eachof said coils.